Lab: Formation of Magnesium Oxide
Name
Lab panner's nam
Other lab partner's nam
Procedure:
1. Heat
a clean crucible and its
lid in a hot flame for l-2minutes. Allow to cool.
2. Inspect your crucible for cracks. If you have a crack, you
will
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need to obtain a different crucible from your
instructor.
3. Obtain the mass of the crucible and its lid. Record on the data table
4. Your instructor will give you
a piece
of Mg ribbon. Wind it into
(see back).
a loose sphere.
5. Add the Mg sphere to the crucible, and obtain the mass of the crucible, lid, and Mg together. Record.
6a. Put the crucible with Mg (no lid yet) in the clay triangle. Light the bunsen burner and adjust it to a hot flame.
You should have
a blue cone, and the tip of the cone should be at the height of the crucible.
6b. V/ith tongs, hold the crucible lid nearby, and wait for the Magnesium to ignite. When it does ignite,
IMMEDIATELY put the crucible lid on.
7. After about 30 seconds, lift the lid to allow air to enter the crucible. Once the Mg flares up, put the lid back
8.
Repeat step 7 several times, until the Mg no longer flares up when then
9. Adjust the crucible lid
off the bunsen burner.
so that a small gap is present to allow air
in.
on.
lid is removed.
Heat it for five more minutes, and then turn
10. Allow the crucible to cool for several minutes. When it is cool enough that you can comfortably hold it, take
it to the balance to find the mass of the crucible, lid, and the magnesium oxide that formed. Record.
1l.
Clean
up: Scrape the powder from the crucible into the trash. DO NOT use water. Return the crucible to the
clay triangle.
Purpose: (At least one of your purposes must
be quantitative)
1
,
Equation: V/rite
a balanced equation
for the reaction of magnesium with oxygen. Include phase subscripts.
Oualitative Data:
Describe the magnesium (before the reaction)
Describe the magnesium oxide (after the reaction)
Is masnesium a metal or
nonmetal?
ls oxvgen a metal or a nonmetal?
Is magnesium oxide an ionic or covalent compound
Is magnesi um combustible?
Is magnesium oxide combustible?
Ouantitative Data
Calçulations (show all work, with units, labels, and sig figs!)
1. a. Calculate the mass of magnesium used in this experiment.
b.
Calculate the mass of magnesium oxide in the crucible at the end of the experiment.
c.
Calculate the mass of oxygen in the magnesium oxide product.
2.
Use your lab data to calculate the empirical formula for the magnesium oxide that formed.
3.a. What should the empirical formula for magnesium oxide be, based on ion charges?
b. How does your empirical formula (from#2)
compare?
4.
Use your lab data to calculate the percent magnesium in magnesium oxide.
5.
Based on your answer to 3a, calculate the percent magnesium in magnesium oxide, using the periodic table.
6. Calculate your percent error for
percent enor
the ToMg:
= | lab value - book vald x
I00Vo
Book value
On lab day, you will receive a list of conclusion questions.
Do these, and staple them to your lab report when you turn it in!
Conclusion Questions for the Magnesium Oxide Lab Name:
Use Conplete Sentenccs to answer these questions!
(Most future lab conclusions will be in paragraph form)
1. Briefly
2.
summarize the purposes of the lab.
Summarize/state the results you got for the percent magnesium and for the emipirical formula.
3. Foreachsourceoferrorlistedbelow,statewhethcrtheenorwouldcausethepercentmagnesiumtocomeouttoohighortoo
low, Explain why the error would cause this, Be specific! Explain clearly how thç enor affects the mass of Mg, O, or MgO, how
this affects numerator or denominator, and therefore how it affects the %Mg in your calculations.
a, The magnesium
(Turn over!)
not have enough time, or did not get hot enough, to completely combust/burn,
b. Tiny red'hot
sparks of magnesium oxide flew out of the crucible when the lid was lifted
have formed a small amount of magnesium nitride or magnesium carbonate, instead of
magnesium oxide, a, Write the formula for magnesium nitride.
b, Write the formula for magnesium carbonate.
Which one of these compounds would cause the percent magnesium to come out too-bigh, if the compound formed instead of
magnesium oxide, Explain your answer,
4. When the magnesium burns, it could